Abstract Details

Name: Subhash Bose
Affiliation: KIAA, Peking University, China
Conference ID: ASI2017_1332
Title : Multiwavelength investigation of Core- Collapse Supernovae
Authors and Co-Authors : Subhash Bose (ARIES), Brijesh Kumar (ARIES)
Abstract Type : Thesis
Abstract Category : Thesis
Abstract : Core-Collapse supernovae (CCSNe) are the end fate of massive stars with wide range of properties and so the observable parameters of these explosions are also very diverse. Circumstellar environment and history of pre-SN evolution also plays a key role in diversifying their properties. In this thesis we characterize a number of CCSNe events which has been extensively observed in photometric, spectroscopic and polarimetric modes at optical wavelengths. This thesis utilizes data collected primarily from telescopes in India viz. 104cm ST and 130cm DFOT at ARIES, 2mIGO at IUCAA and 2mHCT at IIA. Complementary data were also collected from several international network of telescopes and Swift UVOT observations. Our primary goal was to understand various mechanisms involved in the explosion and how they govern observable parameters. We utilized the observational data to constrain progenitor properties, explosion parameters and also to probe circumstellar environment to infer their pre-SN evolution which the progenitor might have undergone. We characterize five CCSNe events (SNe 2012aw, 2013ab, 2013ej, 2013hj and 2014G) in detail. Along with the determination of various physical parameters by modeling the observables, we also probe peculiarities which they exhibit in their observed light curves and spectra. Our detailed observations and spectroscopic modelling revealed ejecta-CSM interaction in SNe 2012aw and 2013ej, and also signature of emergence of recombination phase for the first time in SNe II. Such detections are crucial to improve our understanding of these event. Another vital component of this thesis is utilizing type II SNe as a distance estimator, which has immense cosmological as well as astronomical importance. SNe due to high intrinsic brightness are always an attractive probe for extragalactic distance measurements, however SNe II require an approach which is entirely different than standard candle methods. We implement Expanding photosphere method (EPM) to estimate distances to host galaxies of eight type II SNe and also introduce some improvements in the existing methodology. Our study explored various issues and uncertainties involved in EPM and also demonstrated its potential as a reliable redshift independent technique.